Packing



May 11, 1943.-

G. CHRISTENSON PACKING Filed March 5, 1940 12 K0 2'2 20 La INVENTOR.

ATTORNEY. 4

Patented May 11, 1943 PACKING George Christenson, Plainfleld, N. J.,assignor to Johns-Maurine Corporation, New York, N. Y.,

a corporation of New York I Y Application March 5, 1940, SerialN0.'322,282

'1 Claims. (01. sea-am The present invention relates to cylinder andpiston assemblies, and particularly to those applicable to power reversegear mechanisms, alr

brake mechanisms and the like. The invention is more particularlyconcerned with an improved packing to be employed in such cylinderpiston assemblies.

Cylinder and piston assemblies of the type referred to above nowconventionally include a packing having a base resting upon the pistonhead and an out-turned lip or flange for sliding and sealing engagementwith the cylinder wall.

" Packings of this description are normally referred to as "cup packingsand such terminology will be hereinafter employed. The cup packing isretained in position on the piston head by means of a keeper ring and aplurality of bolts or studs extending through the keeper ring and thebase -of the cup packing, and into the piston head.

The principal object of. the present invention is to provide an improvedcup packing having greater resistance to wear, and hence, longerlifethan those heretofore employed.

Another object o the invention is the provision of a cup packing adaptedto achieve the above-referred to desideratum by means of an inner, morecompressible and fluid-impervious layer, and an outer harderwear-resistant layer.

A further object of the invention is the provision of an improved cuppacking including means 'to insure an air-tight seal between the pistonhead or other element of the piston assembly, and the base-of the cuppacking.

A: still further object of 'the invention is the pr.""'sion of a cuppacking as referred to above, w ,ch will insure againstair or otherfluid from passing from the cylinder at' one side of the piston to theother.

My invention will be more fully understood and further objects andadvantages thereof will belarged scale of a portion of a cup packing ofthe invention;

is; an enlarged sectional view taken on the lined-4 of Fig. 3; and

Fig. 5 is an enlarged detail view of the portion of the packingindicated at A in Fig. 4.

Referring now particularly to Fig. 1, there is disclosed a pistoncylinder assembly of generally conventional design; The assemblyincludes a double acting piston it, carried by a piston rod l2, adaptedfor reciprocation within a cylinder It. The piston ID has a head or seatIS on which rests a cup packing 20. Resting on the cup packing is anannular separator ring 22, which supports a second cup packing 20. Thetwo pa'ckings 20 have their lips or flanges 24 oppositely directed asindicated. A keeper ring 26 is seated upon the second cup packing, andbolts or studs 28 extend through the keeper ring 26, spreader ring 22and packings 20, and are in threaded engagement with the piston head It.The bolts or studs carry nuts or heads 30, which as the bolts aretightened up, are in jamming engagement with the keeper ring to maintainthe several elements of the piston in firmly assembled relationship. Theflanges or lips of the cup packings are forced outwardly against thepiston walls by expander rings 32 of any suitable type.

A piston assembly of the type with which the present invention isparticularly concerned, includes a bore 34 in piston rod l2, one end ofthe bore being in communication with the atmosphere outside of thecylinder, as indicated at 36, and the other end positioned tocommunicate with a passageway 38 in the piston head l0. Passageway 38connects with a radially extending passageway 40, in connector ring 22,through a perforation 42in the cup packing adjacent the piston head.Passageway 38 opens into a groove 44 formed in the peripheryof theseparator ring.

The connecting passageways as above described, are provided to permitthe escape to the atmosphere of I air or other fluid acting upon, oracted. upon by, the piston which may seep past the lips of the cuppackings. thus vent the peripheral space between the lips of thepackings. By this means, air or other fluid which may leak past the lipof either of the packings passes to the atmosphere, rather thancontinuing past'the other cup packing and to the cylinder at theopposite side of the piston.

Referring now particularly to Figs. 1, 4 and"5.. a cup packing I6 isdepicted embodying the" features of the instant invention, andparticularly adaptable for use in a piston andcyl'l'n der assembly ofthe type heretofore described. The

cup packing comprises a base 50, having an inner face 52, an outer face54, and an upstanding lip or flange 56 with an outer face 58, adaptedfor The passageways heretofore possible.

sliding and sealing engagement with the cylinder wall. The cup packingis composed of a plurality of layers of fabric impregnated with amaterial such as a rubber composition, and welded into a substantiallyunitary homogeneous body by molding under heat and pressure. To providethe yieldability necessary for the flange 56 to conform with the normalirregularities of the cylinder walls to reduce leakage past the flangeto the minimum, and at the same time to provide for resistance to wearand deterioration in service to an extent not heretofore possible, theseveral fabric layers adjacent opposite faces of the packings are ofdifferent characters. Thus, in accordance with the preferred form of theinvention, the fabric layers 60 adjacent the inner surface of the cupare of conventional type, comprising preferably a Woven asbestos fabricsuitably impregnated with a material such as a rubber composition. The,fabric layers 62 adjacent the outer surface of the cup however, arecomposed of intercrossed strands of wire-reinforced yarn. This yarncomprises in its preferred form, a core formed of one or more strands ofvery fine. preferably brass wire, around which is wrapped or doubledfibrous strands, preferably asbestos. but which also may be cottonfibres or the like, or mixtures of the different fibres. Thewire-reinforced fabric is impregnated with a suitable rubber or similarcomposition, similarly as the fabric layers 50, and the several layersare joined by molding under heat and pressure into a substantiallyintegral body, as previously referred to.

The wire-reinforced fabric layers 5?: provide a relatively hardwear-resistant surface, enabling the cup to give satisfactory servicefor periods not At the same time the relatively yieldable moreconformable character of the inner layers 56 of substantiallyconventional construction, impart to the entire cup the necessaryyieldability and conformability, to permit the expander ring 32 to holdflange or lip 55 in tight engagement with the cylinder wall. Thus, bycombining the two types of fabric in the manner described, increasedlength of service is obtained without loss of effectiveness of sealingaction between the cup lips or flanges and the cylinder walls.

In the operation of piston cylinder assemblies of the type herespecifically considered, namely, those in which a vent is provided forthe peripheral space between the packing flanges, difficulties havearisen in securing a sufficiently tight fit between the faces 52 and 5dof the packings, particularly the innermost packing including theaperture 32, and the piston head and separator ring, to prevent fluidpenetrating between the smooth shanks of bolts 28 and the walls of thesomewhat enlarged perforations in the keeper ring, etc. through whichthe shanks pass, from findin its way to the escape vent at aperture 42,with consequent loss of pressure from the head end of the cylinder. Thisdifficulty is due to the inevitable inequalities in the large flatsurfaces of the piston head, separator plate, and/or keeper plate, andis accentuated in the instant case by the relatively unyieldingcharacter of the fabric forming the outer layers of the cup packing.

In accordance with the instant invention, this difilculty is overcome byproviding preferably both faces 52 and 54 of the cup packing base with aplurality of concentric ribs BI, and transversely extending cross ribs66 (see particularly Figs. 2, 3 and 4) the ribs 84 and 68 being of thesame height. These ribs, which may be formed during the molding actionand are preferably substantially entirely composed of the rubber orsimilar composition serving as the impregnant for the fabric layers,greatly reduce the area of contact of the cup packing base and thepiston or piston element, with the result that the packing relativelyreadily conforms with the surface of the piston or piston element. Inother words, the numerous relatively narrow, compressible ridges maybeeasily forced into contact with the piston elements over the entireextent of the ridge surfaces, by tightening of the bolts 28. The crossribs 66 are located, at least on both sides of perforation -32, tocompletely dam the grooves between the ridges, and prevent the air orfluid entering the grooves atthe bolt openings'from reaching theperforations 12. Hence, this arrangement provides for the desiredintimate association between the cup base and the piston or pistonelement throughout their contiguous areas, while at the same time,sealing oi the grooves.

Although the cross ridges have been found V: be essential only for thecup packing which illcludes "the perforation :32, they are suitablyformed in all the cup paclrings to provide for interchangeability, andthe necessity of stocking only one type. The concentric and cross ribsare as indicated above, particularly advantageous when employed incombination with a cup pack;- ing having the wire-reinforced outerfabric layers, inasmuch as such layers are even less conformable withthe inequalities of the piston head than conventional types.

Having thus described my invention in rather full detail, it will beunderstood that these details need not be strictly adhered to, but thatvarious changes and modifications will suggest themselves to one skilledin the art, all falling within the scope of the invention as defined bythe subjoined claims.

What I claim is:

l. A cup packing for assembly with a reciprocable piston includingsurfaces confining a por. tion of the cup packing therebetween, said cuppacking comprising a base composed of fabric and a yieldable plasticimpregnant,'to be confined by said surfaces, and a peripheral upstandinglip for sliding and sealing engagement with the cylinder wall, a ventingmeans including an aperture in said base, concentric ribs extending fromthe faces of said base to reduce the area of contact of said surfacesand faces, and transverse ribs damming the valleys between saidconcentric ribs at opposite sides of said aperture, said transverse andconcentric ribs being composed substantially entirely of said plasticimpregnating material.

2. A piston assembly comprising a piston head including a flat annularsurface, a cup packing having a base resting on said surface, a ringoverlying said base, bolt means extending through aligned perforationsin said base and ring, and in threaded engagement with said head, and aventing means including an aperture in said base, said base havingconcentric ribs extending from the faces thereof and in contact withsaid surface and said ring, and transverse ribs damming the valleysdefined by said first-mentioned ribs at both sides of said aperture.

3. A piston assembly comprising a piston head including a flat annularsurface, a cup packing having a base resting on said surface, and aretaining ring overlying said base, bolt means extending through alignedperforations in said base and ring and in threaded engagement with saidbase, a venting means including an aperture in said base, and saidbasebeing composed of fabric impregnated with deformable plastic material,

cable piston including surfaces confining a portion of the cup packingtherebetween, said cup packing comprising a unitary body including abase to be confined by said surfaces, and a peripheral upstanding lipfor sliding and sealing engagement with a cylinder wall, said body com-.

, prising an outer portion including a plurality of and havingconcentric ribs extending from the faces thereof and in contact withsaid surface and said ring, and transverse ribs damming the valleysdefined by said first-mentioned ribs at both sides of said aperture,said ribs being composed substantially entirely of said deformableplastic material.

4. A cup -packing comprising a. base portion and an upstandingperipheral lip including a surface for sliding and sealing engagementwith a cylinder wall, said cup packing including a layer adjacent saidsurface comprising a wirereinforced fabric composed of yarns including a-metal core member and a fibrous covering, and

a yieldable rubber-like impregnant, and an inner layer substantiallyintegral with said first-named layer, and comprising asbestos fabric anda yieldable rubber-like impregnant.

5. A cup packing comprising a unitary body including a base portion andan upstanding peripheral lip, said body comprising an outer portionincluding a plurality of layers of wire-reinforced fabric composed ofyarns including a metal core member and a fibrous covering, and an innerportion composed of non-reinforced asbestos fabric,- said body carryinga yieldable rubber-like impregnant.

6. A cup packing for assembly with a recipro- I engagement with acylinder wall, said body comprising an outer portion including aplurality of layers of wire-reinforced fabric composed of yarnsincluding a metal core member and an asbestos fibre covering, and aninner portion,

composed of non-reinforced asbestos fabric, said body carrying ayieldable rubber-like impregnant, and including concentric ribsextending from the faces of said base to reduce the area of contact ofsaid surfaces and faces, and transverse ribs damming the valleys betweensaid firstmentioned ribs, said ribs being composed substantiallyentirely of said yieldable rubber-like material. 0 v

- GEORGE CHRISTENSON.

